Effect of the Processing and Heat Treatment Route on the Microstructure of MoS2/Polyetheretherketone Coatings Obtained by Electrophoretic Deposition

In this work, molybdenum disulfide nanosheets were electrophoretically co-deposited with PEEK 708 microparticles to fabricate composite coatings on Ti-6Al-4V titanium alloy substrates. Different dispersion media, pure ethanol and ethanol with the addition of cationic chitosan polyelectrolyte have been studied. The co-deposition mechanisms were indicated based on zeta potential measurements and investigation of the interaction between particles in the suspension using electron microscopy. The composite coatings deposited from the suspension containing a low amount of MoS 2 stabilized by chitosan were homogeneous. The polymer morphology changed as a result of heat-treatment from granular in the as-deposited coating into a dense, continuous matrix in the heat treated coating. The separate MoS 2 nanosheets and their packages were relatively homogeneously distributed and formed arrays that were mainly parallel to the coating surface. The coatings exhibited an amorphous structure regardless of the applied cooling rate after heating. The amorphization of the coating, slowly cooled after heating above the melting point, is due to the partial diffusion of sulfur from MoS 2 to PEEK 708 and its sulfonation. The obtained results provide new knowledge regarding the co-deposition mechanisms of MoS 2 and PEEK in the presence of chitosan and polymer sulfonating at elevated temperatures.